Parentheses Fuzz signal tracing

[Timpecter]

I've built a Parentheses fuzz. None of the Distortion, Octave or Boost are working. I've started tracing the signal and it seems to stop at Q1. I've got my input signal at pin 3 and +9v at pin 1 but don't seem to be getting anything from pin 2 - should I be seeing an amplified version of the signal there? I sourced my PF5102 from a supposedly reputable seller on ebay but is it possible it's defective?

 

[Nostradoomus]

Anything is possible on eBay!

Try another n channel jfet if you have them. I used 2n5458s in mine I think.

 

[Timpecter]

Bingo, I swapped the first one out for a 2n5457 and the signal passes. I will see if I need to replace the second 5102 as well but I'm currently puzzling about what seems to be an intermittent mechanical problem with my filter pot...

 

[Nostradoomus]

Any more detail? I would swap the other one out too just in case.

 

[Timpecter]

I swapped both of the 5102s out for 2n5457s and the signal passes through fine. I have a couple other issues though:

1) The boost potentiometer only seems to work when it is not attached to the enclosure. I had to swap out one of the other pots because of the same problem. I can't see that the solder tags are touching the inside of the enclosure so I'm not sure what's happening here. Any ideas?
2) I can't hear any appreciable octave effect at all. There is no difference in sound with the switch on or off. There is no change in sound when I turn the octave blend pot.
3) When I plug in the guitar get a nice distortion sound when I strike a note or chord, but it quickly sputters out without sustain - a bit like I've heard when I have had a dying battery on other distortion pedals. But I'm powered off a 9v 1A wall wart. Is there anything I should look for to solve this problem?

 

[Nostradoomus]

Post some pictures of the top/bottom of your board and your wiring for jacks/switches as well. We’ll get to the bottom of it!

The octave section is fairly sensitive to the diodes being matched for forward voltage.

 

[Timpecter]

I’m stumped! I’ve taken it out of its enclosure and it sounds the same.

 

[Nostradoomus]

Do you have a way to test your transistors and jfets? Whereabouts did you source your parts?

 

[Timpecter]

I spent some time on this with my oscilloscope and a test signal today. The faulty PF5102s came from ebay but the 2n5457s I've used to replace them seem to be working just fine. I actually think there's some mechanical problem with the A100k pots - if I jiggle the connections and shaft around a bit I get a proper signal passing through.

One useful thing I figured out how to do was take some screen shots off my 'scope. This is a sine wave test signal in yellow and the wiper on the octave control at about midway in blue. Is that what I should expect to see?

 

[Chuck D. Bones]

What do you get on pin 3 of the OCTAVE pot?

 

[Timpecter]

Sorry for the somewhat inconsistent responses to the suggestions here! But I have had some success. As I suspected there seemed to be something wrong with the batch of 100k pots I had. I swapped those out and it immediately worked. Although then it was super noisy so I went and shortened the leads right down. That helped a huge amount. Now, I get a high pitched whine when using the cheap wall wart I had on hand but it sounds great using a 9 volt battery. I assume I need a regulated power supply? Anyway here’s a pic:

 

[Nostradoomus]

A good isolated supply is crucial. I just spent a few hours chasing some motorboating in a Hyped Fuzz build only to realize I was using a wall wart instead of my voodoo lab ISO 5. Cleared it right up.

 

[Chuck D. Bones]

Nice front panel. Hypnotizing.
I've had my share of 9V power supply issues too. Always good to test with a battery to find out if the PS could be the culprit.